This story has been updated.
WASHINGTON (AP) -- Top congressional lawmakers struck a long-sought, bipartisan agreement Thursday for the broadest trade policy pact in years, allowing President Barack Obama to negotiate trade accords for Congress' review and move forward with talks on a sweeping partnership with Pacific nations.
Obama quickly said he will sign the bill if Congress passes it.
"It's no secret that past trade deals haven't always lived up to their promise," Obama said in a statement. "And that's why I will only sign my name to an agreement that helps ordinary Americans get ahead."
Chief among the challenges of passing the bill are divisions within the president's own party. Liberal and pro-business Democrats are bitterly split over the deal's potential for creating or subtracting American jobs. Under the legislation, Congress gets an up-or-down vote on any such deals, but in exchange cannot make changes - a concern for labor, environmental and other interest groups. The divisions hover over 2016 presidential politics, too, as Democratic contender Hillary Rodham Clinton kicks off her campaign to unite the party.
House Speaker John Boehner applauded the deal but said much of the burden of its success rests with Obama.
"He must secure the support from his own party that's needed to ensure strong, bipartisan passage," Boehner said in a statement that was echoed by the U.S. Chamber of Commerce.
For Obama, the "fast track" legislation comes at an opportune time. He's negotiating the Trans-Pacific Partnership, which proposes a trade agreement involving the United States, Japan, Vietnam, Canada, Mexico and seven other Pacific rim nations.
Labor unions and others say the Pacific pact would hurt U.S. job growth and encourage other countries to abuse workers and the environment. The Obama administration rejects those claims, and says U.S. goods and services must have greater access to foreign buyers.
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One Democrat, Sen. Sherrod Brown of Ohio, said the agreement marked only a start and could be derailed by amendments that might be added when lawmakers consider the bill in committees or on the floor.
Brown and other Democrats who are aligned with organized labor are often highly suspicious of, or even hostile to, trade legislation. They argue such measures facilitate agreements that wind up destroying jobs in the U.S. and creating jobs in nations that lack the environmental and worker safety protections that exist in the United States.
"Negotiating objectives without enforcement mechanisms don't get you very far," Brown told reporters.
"Over and over again, we've been told that trade deals will create jobs and better protect workers and the environment," said Sen. Bob Casey, D-Pa. "Those promises have never come to fruition."
Not only did Obama express support, but Secretary of State John Kerry and Defense Secretary Ash Carter each issued statements welcoming the bipartisan bill.
Sen. Orrin Hatch, R-Utah, chairman of the Senate Finance Committee, said he expects the committee to consider the legislation next week.
"Over and over again, we've been told that trade deals will create jobs and better protect workers and the environment. Those promises have never come to fruition."'
Traditionally, trade legislation has also been accompanied by a parallel bill that provides funding under the Trade Adjustment Assistance program for American workers who are adversely affected by international accords. Sen. Ron Wyden, D-Ore., and Sen. Susan Collins, R-Maine, unveiled the parallel bill shortly after the trade agreement was announced.
Wyden also introduced separate legislation to renew an expired health care tax break for workers eligible for trade adjustment assistance. The bill would provide a tax credit equal to 72.5 percent of the cost of health insurance.
The past several presidents have had so-called trade promotion authority, under which Congress may vote yes or no on proposed international deals, but not amend them. The deal was announced Thursday by Hatch, Wyden and House Ways and Means Committee Chairman Paul Ryan, R-Wis.
Authority lapsed in 2007, and Obama is seeking its reinstatement at the same time the administration is pursuing global deals.
Approval of the legislation will be challenging, given the opposition trade bills draw from Democrats and the opposition of Republicans who deeply oppose Obama's policies and say they are reluctant to increase his authority in any area.
Rep. Sander Levin of Michigan, the top Democrat on the House Ways and Means Committee, said the bill "puts Congress in the back seat and greases the skids for an up-or-down vote after the fact. Real congressional power is not at the end of the process, it is right now when the critical outstanding issues are being negotiated."
A statement from the footwear industry, the Footwear Distributors and Retailers of America, hailed the legislation moments after it was announced. In a statement, the group said a Trans Pacific Partnership Agreement had the potential to "save the footwear industry and American consumers hundreds of millions of dollars a year in costs."
Labor unions have traditionally opposed trade legislation and swiftly criticized the legislation.
Teamsters General President Jim Hoffa said the bill "would allow secret trade pacts to sail through Congress with no chance to alter them. That's bad for American workers as well as their families."